WO2012144644A1

WO2012144644A1 - Crosslinked product of cyclic olefin resin, and process for producing same

Info

Publication number: WO2012144644A1
Application number: PCT/JP2012/060849
Authority: WO
Inventors: 浩一梅本; 市川　晴雄
Original assignee: 株式会社ダイセル
Priority date: 2011-04-21
Filing date: 2012-04-23
Publication date: 2012-10-26
Also published as: KR20130136589A; JPWO2012144644A1; EP2700668A4; TW201302821A; EP2700668A1; CN103619924A; JP5155500B2; US20140044950A1

Abstract

A crosslinked product of a cyclic olefin resin can be prepared by crosslinking a copolymer of a linear olefin and a cyclic olefin with an electron beam or the like. The cyclic olefin comprises a bicyclic olefin. The content ratio of the cyclic olefin is more than 15 mol% and up to 40 mol% relative to the total amount of the linear olefin and the cyclic olefin. The copolymer of the linear olefin and the cyclic olefin has a glass transition temperature of 20-80ºC or has a degree of crystallinity of 1% or less. The crosslinked product may have a haze value of 2% or less. The crosslinked product according to the present invention has both heat resistance and flexibility while keeping a low haze value and high transparency.

Description

Crosslinked product of cyclic olefin resin and method for producing the same

The present invention relates to a crosslinked product of cyclic olefin resin which has transparency, heat resistance and flexibility and can be used in various fields such as electric and electronic devices or optical devices, and a method for producing the same.

Since cyclic olefin resins are excellent in transparency, chemical resistance, moisture resistance, mechanical properties, etc., optical parts such as lenses and optical recording materials, parts for electricity or electronics such as printed circuit boards and connectors, containers for medicines and the like It is used in various fields such as medical or medical equipment supplies such as syringes, experimental instruments such as beakers and optical cells, and automobile parts. However, while the field of application is expanded, cyclic olefin resins have characteristics of low flexibility, insufficient moldability, high glass transition temperature, but low softening temperature, so various kinds of them depending on the application. The improvement of is being considered.

For example, as a resin composition for adhering to a metal layer of a printed wiring board, JP-A-2005-47991 (Patent Document 1) discloses that an organic peroxide of 0. A crosslinkable resin composition is disclosed in which 3 to 2.5 parts by weight, 7 to 30 parts by weight of a coagent, and 5 to 100 parts by weight of an inorganic filler are dispersed. In this document, a crosslinked molded article having high plating adhesion and solder heat resistance can be obtained by heating the crosslinkable resin composition to crosslink it.

Further, as an optical material or medical material such as an optical lens or an optical film, JP-A-2006-274164 (Patent Document 2) discloses that a molded product made of a cyclic olefin polymer has an acceleration voltage of 50 kV or more and an irradiation dose of 50. A method is disclosed in which radiation is irradiated at a surface temperature (Tg-50) to (Tg + 70) ° C. of an irradiated part of ̃1000 kGy. This document describes that the cyclic olefin polymer is irradiated with radiation to broaden the molecular weight distribution and improve the formability. The cyclic olefin polymer is a polymer containing 10 mol% or more of cyclic olefin units, and is described as preferably having a glass transition temperature of 100 ° C. or more. In the examples, a cyclic olefin polymer having a glass transition temperature of 58 to 140 ° C. is irradiated with β-rays at a surface temperature of 75 to 180 ° C. of the irradiated portion to produce a molded body without deformation. Incidentally, this document does not describe crosslinking.

However, these molded articles can not be used for applications requiring flexibility because of their low flexibility. Furthermore, in this method, radiation such as beta rays is irradiated at high temperature, but since a heating device is not attached to a normal radiation irradiation device, productivity is low. In particular, it is difficult to produce a crosslinked product having a high crosslinking density and high heat resistance and durability. Further, in Example 2 of Patent Document 2, a sheet is produced in which a cyclic olefin polymer (APEL 8008T) formed of a tetracyclic olefin and having a glass transition temperature of 58 ° C. is irradiated with β-rays, Even with this sheet, transparency, heat resistance and appropriate flexibility can not be simultaneously achieved. In particular, since it is difficult to heat at a high temperature from the viewpoint of optical element protection in the case of a sealing material of an optical element (especially an electronic device etc.) which is required to be transparent, it is appropriate to soften at about 30 to 80 ° C. Although flexibility (low-temperature melting or softening) is required, even this sheet does not satisfy such flexibility. In addition, because tetracyclic olefins have a bulky structure, it is necessary to increase the ethylene content if appropriate flexibility (low-temperature melting or softening) at low temperatures is required, but the ethylene content is high As a result, ethylene chains are inevitably crystallized, haze is increased, and it is not suitable for optical applications. On the other hand, although it is necessary to increase the glass transition temperature in order to reduce haze, it loses moderate flexibility (low-temperature melting property or softening property) at low temperature. Furthermore, when the glass transition temperature is lowered, the heat resistance is also inevitably lowered, and thus both are in a trade-off relationship, and it has been common technical knowledge of those skilled in the art that coexistence of these characteristics is difficult.

Further, in JP-A-11-340590 (Patent Document 3), 5 to 400 parts by weight of a resin excellent in radiation crosslinkability with the norbornene-based resin and 100% by weight of a thermoplastic norbornene-based resin There is disclosed a laminate for a printed wiring board having a radiation cross-linked structure, having a conductive metal foil in a sheet formed of a resin composition containing 0.1 to 20 parts by weight of an auxiliary. In this document, high solder heat resistance is imparted by crosslinking a thermoplastic norbornene resin with a radiation crosslinkable resin such as polybutadiene, and the resin is tightly integrated with a metal foil.

However, in this resin composition, a radiation crosslinkable resin is essential, and the characteristics of the norbornene resin are degraded. Furthermore, the composition is deformed by the irradiation of radiation.

On the other hand, as a material that can be used in various fields such as films, sheets, containers, packaging materials, automobile parts, electric and electronic parts, building materials, civil engineering materials, etc., Japanese Patent No. 3274702 (patent document 4) A layer containing a cyclic olefin-based copolymer having a temperature of 30 ° C. or less, a layer or a molded article comprising at least one material selected from synthetic polymers, natural polymers, metals, metal oxides and mixtures thereof A multilayer material consisting of is proposed. In the examples of this document, cyclic olefin copolymer films having a crystallinity of 1%, a glass transition temperature of 2 ° C. or 3 ° C., and a melting point of 81 ° C. or 73 ° C., LLDPE sheet, nylon 6 sheet, polyimide sheet or aluminum plate Is heat laminated.

However, cyclic olefin copolymers having a low glass transition temperature lack heat resistance and deform easily, for example, when exposed to high temperatures in the process of using the final product after film forming.

Furthermore, in JP-A-6-345885 (Patent Document 5), a copolymer [a] formed by addition polymerization of an α-olefin and a cyclic olefin, and a polymer formed by ring-opening polymerization of cyclic olefins [ b), a ring-opened copolymer thereof [c], and a hydrogenated substance thereof [a '], [b'] and [c '] having a glass transition temperature (Tg) of 50 ° C. or higher The cyclic olefin resin crosslinked body obtained by processing the one or more cyclic olefin resin which is these by an electron beam or radiation is disclosed. In this document, the molar percentage of α-olefin and cyclic olefin is described as 80:20 to 99.9: 0.1. The glass transition temperature is preferably −30 to 45 ° C. (especially −30 to 40 ° C.), and the degree of crystallinity is described as 0 to 40% (especially 0 to 25%). Furthermore, in the examples, an ethylene-norbornene copolymer having a norbornene content of 10.1 mol%, a glass transition temperature of 4 ° C., a crystallinity of 2.0%, or a norbornene content of 5.6 mol%, a glass transition temperature of 1 ° C. An ethylene-norbornene copolymer having a crystallinity of 4.3% is irradiated with γ-rays to produce a sheet.

However, this sheet has a large amount of ethylene chains and exhibits crystallinity, and has low transparency. Therefore, it is intended for use in medicine, packaging, food fields such as infusion bags, and the transparency is low, and in particular, it does not have the transparency required in the field of optical elements and the like. Furthermore, this sheet is intended to impart sufficient elasticity and flexibility in the above-mentioned field, and the elasticity is too high and does not have appropriate flexibility.

JP 2005-47991 A (claim 1, paragraph [0066] [0106]) JP, 2006-274164, A (claim 1, paragraph [0009] [0022] [0034], an example) JP-A-11-340590 (claim 1, paragraph [0041]) Patent No. 3274702 (Claims, paragraph [0019], Example) Japanese Patent Application Laid-Open No. 6-345885 (Claims, Paragraphs [0001] [0005] [0066] [0069] [0086], Examples)

Therefore, an object of the present invention is to provide a crosslinked product of cyclic olefin resin that can achieve both heat resistance and flexibility (especially low temperature softening property) while maintaining high transparency with low haze, and a method for producing the same. It is in.

Another object of the present invention is a crosslinked product of cyclic olefin resin having high transparency and excellent durability (stability) such as water resistance, weather resistance (especially light resistance) and chemical resistance, and a method for producing the same To provide.

Still another object of the present invention is to provide a crosslinked product of cyclic olefin resin excellent in moisture resistance and mechanical properties and a method for producing the same.

Another object of the present invention is to provide a method for easily producing a crosslinked product of a cyclic olefin resin excellent in transparency, heat resistance and flexibility (in particular, low temperature softening property).

As a result of intensive studies to achieve the above-mentioned problems, the inventors of the present invention crosslink a specific linear olefin-cyclic olefin copolymer with an electron beam or the like, while maintaining high transparency with low haze. The inventors have found that heat resistance and flexibility can be compatible and complete the present invention.

That is, the crosslinked product of the present invention is a crosslinked product of a chain olefin-cyclic olefin copolymer containing a chain olefin and a cyclic olefin as a polymerization component, wherein the cyclic olefin contains a bicyclic olefin, and the cyclic The proportion of the olefin is more than 15 mol% and 40 mol% or less based on the total of the chain olefin and the cyclic olefin, and the glass transition temperature of the chain olefin-cyclic olefin copolymer is 20 to 20 It is 80 ° C.

In the present invention, a crosslinked product of a chain olefin-cyclic olefin copolymer comprising a chain olefin and a cyclic olefin as a polymerization component, wherein the cyclic olefin contains a bicyclic olefin, and the proportion of the cyclic olefin is And a crosslink having a crystallinity of 15% or less and 40% or less with respect to the total of the chain olefin and the cyclic olefin and having a crystallinity of the chain olefin-cyclic olefin copolymer of 1% or less The body is also included.

In the crosslinked product of the present invention, the crystallinity of the linear olefin-cyclic olefin copolymer may be 0.5% or less. The crosslinked product of the present invention may have a haze of 2% or less (in particular, 0.1 to 1.5%) in accordance with JIS K7136. The glass transition temperature of the linear olefin-cyclic olefin copolymer may be about 30 to 50.degree. In the crosslinked product of the present invention, the cyclic olefin may be norbornenes, and the molar ratio of the chain olefin to the cyclic olefin may be about chain olefin / cyclic olefin = 84/16 to 75/25. Further, the crosslinked body of the present invention may have a breaking elongation of 10% or more (in particular, 100 to 400%) at a thickness of 100 μm in accordance with JIS K7127. Furthermore, the gel fraction measured by a method of refluxing with toluene for 3 hours may be 5% by weight or more (particularly 70% by weight or more). The crosslinked product of the present invention may have a storage modulus of 100 to 4000 MPa at a temperature of 25 ° C., a storage modulus of 0.01 to 10 MPa at a temperature of 80 ° C., and a molecular weight between crosslinking points of 8,000 to 30,000. The crosslinked body of the present invention may be a crosslinked body substantially free of a resin having a crosslinkable group and a crosslinking agent. The crosslinked body of the present invention may be an electron beam crosslinked body. The crosslinked body of the present invention is in the form of a sheet and may be a sealing material for an optical element.

The present invention also includes a method for producing a crosslinked product by crosslinking a linear olefin-cyclic olefin copolymer with an electron beam or radiation. In this method, crosslinking may be performed with an electron beam without heating, and in particular, may be performed with an accelerating voltage of 150 kV or more and an irradiation dose of 200 kGy or more.

In the present specification, “flexibility” or “moderate flexibility” does not mean softness or elasticity such as rubber or elastomer which can be expanded or deformed at normal temperature or around room temperature, but normal temperature or around room temperature In the above, it means that it is hard (non-elastic) but softens at a relatively low temperature (eg, about 30 to 80 ° C., preferably about 40 to 70 ° C., more preferably about 45 to 60 ° C.). Specifically, “low temperature softening property” means that the film softens at a temperature of about 30 to 80 ° C., and the elastic modulus after softening becomes 100% or less of that before the softening.

In the present invention, since the specific linear olefin-cyclic olefin copolymer is crosslinked by an electron beam or the like, heat resistance and flexibility (especially low temperature softening) are maintained while maintaining high transparency with low haze. Can be compatible. Furthermore, this crosslinked body is high in transparency, excellent in water resistance, weather resistance (especially light resistance), and durability such as chemical resistance, and also excellent in moisture resistance and mechanical properties. Further, in the present invention, a crosslinked product of cyclic olefin resin excellent in transparency, heat resistance and flexibility can be easily produced.

The crosslinked product of the present invention is a crosslinked product of a cyclic olefin resin (a chain olefin-cyclic olefin copolymer) containing a chain olefin and a cyclic olefin as a polymerization component.

(Cyclic olefin resin)
The cyclic olefin resin (uncrosslinked cyclic olefin resin) in the present invention contains a chain olefin and a cyclic olefin as a polymerization component.

Examples of chain olefins include chain C such as ethylene, propylene, 1-butene, isobutene, 1-pentene, 3-methyl-1-pentene, 4-methyl-1-pentene, 1-hexene, 1-octene and the like. _2-10 olefins etc. are mentioned. These linear olefins can be used alone or in combination of two or more. Among these chain olefins, preferred are α-chain C _2-8 olefins, and more preferred are α-chain C _2-4 olefins (especially ethylene).

The cyclic olefin is a polymerizable cyclic olefin having an ethylenic double bond in the ring, and includes bicyclic olefins. Examples of representative bicyclic olefins include norbornene (2-norbornene) which may have a substituent, octalin (octahydronaphthalene) which may have a substituent, and the like. Examples of the substituent include an alkyl group, an alkenyl group, an aryl group, a hydroxyl group, an alkoxy group, a carboxyl group, an alkoxycarbonyl group, an acyl group, a cyano group, an amide group and a halogen atom. These substituents may be used alone or in combination of two or more.

Specifically, as bicyclic olefins, for example, 2-norbornene; 5-methyl-2-norbornene, 5,5-dimethyl-2-norbornene, 5-ethyl-2-norbornene, 5-butyl-2-norbornene Norbornenes having an alkyl group (C _1-4 alkyl group) such as; norbornenes having an alkenyl group such as 5-ethylidene-2-norbornene; 5-methoxycarbonyl-2-norbornene, 5-methyl-5-methoxycarbonyl Norbornenes having an alkoxycarbonyl group such as -2-norbornene; norbornenes having a cyano group such as 5-cyano-2-norbornene; 5-phenyl-2-norbornene, 5-phenyl-5-methyl-2-norbornene, etc. Norbornenes having an aryl group of: octalin; 6-D Examples include octalin having an alkyl group such as chill-octahydronaphthalene.

These bicyclic olefins can be used alone or in combination of two or more. Among these bicyclic olefins, norbornenes such as norbornene and norbornene having an alkyl group (C _1-4 alkyl group such as methyl group and ethyl group) are preferable.

The cyclic olefin may contain a bicyclic olefin, and may further contain a monocyclic olefin and / or a polycyclic olefin having three or more rings. Examples of monocyclic olefins include cyclic C _4-12 cycloolefins such as cyclobutene, cyclopentene, cycloheptene and cyclooctene. Examples of polycyclic olefins include dicyclopentadiene; 2,3-dihydrodicyclopentadiene, methanooctahydrofluorene, dimethanooctahydronaphthalene, dimethanocyclopentadienonaphthalene, methanooctahydrocyclopentadienonaphthalene and the like Derivatives of 6-ethyl-octahydronaphthalene etc .; adducts of cyclopentadiene with tetrahydroindene etc., 3- to 4-mer of cyclopentadiene etc.

In the present invention, although bicyclic olefins are contained as cyclic olefins, it may be because bicyclic olefins (particularly, the above-mentioned norbornenes such as norbornene) have a suitable bulk, or in a specific ratio to chain olefins When combined and crosslinked, a novel polymer is obtained which has properties (i.e., properties compatible with low temperature softening, heat resistance and transparency) which can not be achieved by the conventional polymers. The proportion of bicyclic olefin (particularly norbornene) may be 10 mol% or more, for example, 30 mol% or more, preferably 50 mol% or more, and more preferably 80 mol% or more with respect to the whole cyclic olefin. In particular, it may be 90 mol% or more) and may be a bicyclic olefin alone (100 mol%). When the proportion of bicyclic olefins is small and the proportion of polycyclic olefins having three or more rings (particularly, polycyclic olefins having four or more rings) is large, the composition becomes rigid and the low temperature softening property and the heat resistance can not be compatible. In addition, even if the proportion of the bicyclic olefin is small and the proportion of the monocyclic olefin is large, the low temperature softening property and the heat resistance can not be compatible.

A chain olefin (especially an α-chain C _2-4 olefin such as ethylene) and a cyclic olefin (especially norbornene etc.) from the viewpoint of achieving both transparency and flexibility in the chain olefin-cyclic olefin copolymer The ratio (molar ratio) with respect to (polycyclic olefin) of (1) is that the ratio of cyclic olefin is more than 15 mol% and 40 mol% or less with respect to the total of the chain olefin and the cyclic olefin. In the present invention, by setting the ratio of the cyclic olefin in the above range, the balance between the flexibility and the heat resistance is excellent, and the generation of haze (particularly, internal haze) can be suppressed, and the transparency can be improved.

Further, the ratio (molar ratio) of the linear olefin to the cyclic olefin is, for example, linear olefin / cyclic olefin = 84/16 to 65/35 (eg, 84/16 to 75/25), preferably 83/17. It is preferably about 70 to 30/30, more preferably about 81/19 to 73/27 (particularly about 80/20 to 75/25). When transparency and heat resistance are important, the ratio of both is, for example, linear olefin / cyclic olefin = 80/20 to 62/38, preferably 79/21 to 65/35, more preferably 78/22 to 65 It may be about / 35 (especially 75/25 to 67/33). In particular, from the viewpoint of achieving both transparency, heat resistance and low-temperature softening property, the ratio of the two is linear olefin / cyclic olefin = 84/16 to 75/25, preferably 82/18 to 77/23, more preferably May be on the order of 82/18 to 78/22 (especially 81/19 to 79/21). If the proportion of cyclic olefin is too low, haze will occur, and if it is too high, the flexibility will decrease.

Other copolymerizable monomers include, for example, vinyl ester monomers (eg, vinyl acetate, vinyl propionate, etc.); diene monomers (eg, butadiene, isoprene, etc.); (meth) acrylics Monomers [for example, (meth) acrylic acid or derivatives thereof ((meth) acrylic acid ester etc.) and the like] can be exemplified. These other copolymerizable monomers may be used alone or in combination of two or more. The content of these other copolymerizable monomers is, for example, 5 mol% or less, preferably 1 mol% or less, relative to the copolymer.

The linear olefin-cyclic olefin copolymer may be a resin obtained by addition polymerization, or may be a resin obtained by ring opening polymerization (ring opening metathesis polymerization, etc.). The polymer obtained by the ring-opening metathesis polymerization may be a hydrogenated resin. The polymerization method of the linear olefin-cyclic olefin copolymer may be a conventional method, for example, ring-opening metathesis polymerization using a metathesis polymerization catalyst, addition polymerization using a Ziegler-type catalyst, addition polymerization using a metallocene-based catalyst (usually And ring opening metathesis polymerization) using a metathesis polymerization catalyst.

The linear olefin-cyclic olefin copolymer is amorphous, and the degree of crystallinity is 0 to 3%, preferably 0 to 1%, more preferably 0 to 0.5% (particularly 0 to 0.1%). It is an extent. In the present invention, since the copolymer is amorphous, it is excellent in transparency (light guiding property), and the generation of haze in the crosslinked product can be suppressed. In particular, a crosslinked product in which cyclic olefins (particularly norbornenes) and linear olefins are combined in a predetermined ratio has a crystallinity of about 0% (eg, 0.5% or less, preferably 0.1% or less, and further, Preferably, it is amorphous at 0%) and exhibits excellent transparency since almost no internal haze is observed. Although the cross-linked product of the present invention is non-crystalline having a crystallinity of approximately 0% as described above, when the crystallinity is measured by the following measurement method, crystalline portions are obtained by the method of setting the baseline. In some cases,

The crystallinity degree can be calculated by performing fitting of a crystalline portion (peak) and an amorphous portion (halo) using an X-ray diffraction method and substituting each integrated intensity into the following equation. In the formulae, X represents the crystalline scattering integral intensity (scattering integral intensity derived from the crystalline portion), and Y represents the amorphous scattering integral intensity (scattering integral intensity derived from the amorphous portion).

Degree of crystallinity (%) = [X / (X + Y)] × 100.

The glass transition temperature (Tg) of the linear olefin-cyclic olefin copolymer (before crosslinking) can be selected from the range of about 10 to 100 ° C., but it is preferably 20 to 80 ° C. from the viewpoint of being able to impart appropriate flexibility. For example, the temperature is about 25 to 55 ° C., more preferably about 25 to 75 ° C. (particularly about 30 to 45 ° C.). Furthermore, the glass transition temperature is, for example, 15 by combining cyclic olefins (especially norbornenes) and chain olefins in the above proportion, from the viewpoint of achieving a high degree of compatibility between flexibility (especially low temperature softening) and heat resistance. The temperature is about 50 to 50 ° C. (eg, 30 to 50 ° C.), preferably 20 to 40 ° C. (eg, 30 to 40 ° C.), and more preferably about 25 to 35 ° C. (particularly 30 to 35 ° C.). Furthermore, from the viewpoint of transparency, it may be in a range exceeding 30 ° C., for example, 31 to 50 ° C., preferably 32 to 45 ° C., and more preferably about 33 to 40 ° C.

The number average molecular weight of the linear olefin-cyclic olefin copolymer is, for example, about 1000 to 150000, preferably about 5000 to 120000, and more preferably about 10000 to 100000 (particularly about 20000 to 90000).

The glass transition temperature and the melting point can be controlled by adjusting the proportion of the monomer, the substituent of the monomer, the molecular weight of the polymer, and the like.

(Other olefin resin)
In addition to the cyclic olefin resin, another olefin resin crosslinkable with the cyclic olefin resin may be contained. In the present invention, by using another olefin resin, the crosslinking density can be adjusted to control flexibility and heat resistance. The other olefin resin is not particularly limited as long as it can be crosslinked with the cyclic olefin resin, and a chain olefin resin, a cyclic olefin resin other than the cyclic olefin resin (other cyclic olefin resins) Etc.

Examples of the chain olefin resin include polymers containing the chain olefin exemplified in the section of the cyclic olefin resin, in particular, an α-chain C _2-4 olefin such as ethylene and propylene (particularly ethylene). . Examples of chain-like olefin resins include polyethylene resins, polypropylene resins, and poly (methylpentene-1) resins. These linear olefin resins can be used alone or in combination of two or more. Among these linear olefin resins, polyethylene resins such as low, medium or high density polyethylene and linear low density polyethylene are preferable.

As said other cyclic olefin resin, the said cyclic olefin resin WHEREIN: The ratio of cyclic olefin can use cyclic olefin resin which exceeds 40 mol% with respect to the sum total of linear olefin and cyclic olefin. The ratio (molar ratio) of the chain olefin to the cyclic olefin is, for example, about 50/50 to 0/100, preferably about 40/60 to 10/90. Other cyclic olefin resins can also be used alone or in combination of two or more. Among these other cyclic olefin resins, a norbornene-ethylene copolymer having a ratio of norbornene to ethylene in the above range is preferable.

The glass transition temperature of the other olefin resin can be selected from the range of about -150 ° C. to 200 ° C. according to the type of the olefin resin, and in order to adjust the glass transition temperature of the cyclic olefin resin, cyclic olefin resin Other cyclic olefin resins having a glass transition temperature higher than that of the resin (for example, a glass transition temperature exceeding 100 ° C., about 120 to 200 ° C.), and polyethylene resins having a glass transition temperature lower than the cyclic olefin resin (for example, A glass transition temperature of less than 10 ° C., for example, about −110 to 0 ° C., preferably about −80 to −5 ° C., and more preferably about −50 to about −10 ° C. may be used.

The number average molecular weight of the other olefin resin is, for example, about 5,000 to 300,000, preferably about 10,000 to 200,000, and more preferably about 15,000 to 150,000.

The ratio (weight ratio) of the cyclic olefin resin to the other olefin resin is cyclic olefin resin / other olefin resin = 100/0 to 50/50, preferably 99/1 to 60/40, more preferably May be about 95/5 to 70/30, and from the viewpoint of transparency, the proportion of the other olefin resin may be 20% by weight or less, for example, 100/0 to 80/20 (in particular, It may be about 100/0 to 90/10).

(Crosslinked body)
The crosslinked body of the present invention is obtained by crosslinking the cyclic olefin resin, and has moderate flexibility and high heat resistance. In general, a soft resin has a low glass transition temperature and is flexible but does not have sufficient heat resistance. That is, in the resin, flexibility (especially low temperature softening) and heat resistance are in a trade-off relationship, and it was extremely difficult to establish both simultaneously. On the other hand, the present invention is characterized in that appropriate flexibility and heat resistance are made compatible by crosslinking a specific cyclic olefin resin having a cyclic olefin proportion appropriately adjusted with an electron beam or the like. Do.

The glass transition temperature of the crosslinked product can be selected from the range of about 10 to 100 ° C., for example, about 15 to 90 ° C., preferably 20 to 80 ° C., and more preferably about 25 to 75 ° C. (especially 25 to 50 ° C.). Thus, in the present invention, the rise in the glass transition temperature is small even after crosslinking, and the temperature difference with the glass transition temperature before crosslinking may be 50 ° C. or less, for example, 0 to 40 ° C., preferably 0 to 30. C., more preferably 0 to 20.degree. C. (particularly 0 to 10.degree. C.) and maintaining high flexibility even after crosslinking. In particular, in the present invention, by combining cyclic olefins (particularly norbornenes) and linear olefins in the above proportion, the glass transition temperature at which low temperature softening property can be exhibited can be adjusted, and the glass transition temperature is 25 to 55 ° C., for example. The temperature may preferably be about 30 to 50 ° C., more preferably about 30 to 45 ° C. (particularly about 30 to 40 ° C.).

Furthermore, the crosslinked product may have a breaking elongation of about 10% or more, for example, 50 to 1000%, preferably 80 to 500% (eg, 80 to 500%) in a tensile test (film with a thickness of 100 μm) according to JIS K7127. 100 to 500%), more preferably about 100 to 400% (especially 250 to 350%). Furthermore, since the crosslinked body of the present invention exhibits elastic deformability, it is preferable that the tensile test does not show a yield point.

In the present invention, the heat resistance of the crosslinked product can be indicated by the linear thermal expansion coefficient at 140 to 150.degree. Specifically, the linear thermal expansion coefficient at 140 to 150 ° C. may be 2000 ppm / ° C. or less (eg, 1 to 2000 ppm / ° C.), for example, 5 to 1000 ppm / ° C., preferably 10 to 800 ppm / ° C. More preferably, it is about 50 to 500 ppm / ° C. (particularly about 100 to 400 ppm / ° C.). In the present invention, the crosslinked product does not melt even at a high temperature of 140 to 150 ° C., exhibits a suitable linear thermal expansion coefficient, and maintains excellent heat resistance.

The crosslinked product of the present invention is suitably crosslinked in order to achieve both heat resistance and flexibility (especially low temperature softening). The degree of crosslinking in the crosslinked product can be indicated by the gel fraction measured by a method of refluxing with toluene for 3 hours. The gel fraction of the crosslinked product may be, for example, 5% by weight or more, and for example, 10 to 99% by weight (eg, 30 to 98% by weight), preferably 50 to 97% by weight, more preferably 80 to It may be about 95% by weight (particularly 85 to 93% by weight). In detail, the gel fraction can be measured by the measurement method described in the examples. In the present invention, the crosslink density can be controlled to the irradiation conditions of electron beam and radiation, but by adjusting the proportion of the cyclic olefin to a specific range (in particular, the proportion of the cyclic olefin and the chain olefin is the above By adjusting it, the gel fraction can be adjusted to 70% by weight or more, preferably 80% by weight or more (particularly 85% by weight or more). As a result, the crosslink density of the crosslinker is increased, and the heat resistance and the durability are improved, but the flexibility is maintained at an appropriate level probably because the proportion of the cyclic olefin is appropriately adjusted.

The crosslinked product of the present invention (in particular, a crosslinked product of a copolymer in which a cyclic olefin and a chain olefin are combined in the above ratio) has a storage elastic modulus of 100 to 4000 MPa, preferably 500 to 3000 MPa at a temperature of 25 ° C. And more preferably about 1000 to 2000 MPa (eg, about 1200 to 1800 MPa). The storage elastic modulus at a temperature of 50 ° C. is about 5 to 500 MPa, preferably 10 to 300 MPa (eg, 20 to 280 MPa), and more preferably about 30 to 250 MPa (eg, 50 to 220 MPa). Furthermore, the storage elastic modulus at a temperature of 80 ° C. is 0.01 to 10 MPa, preferably 0.1 to 8 MPa (eg, 0.5 to 7.5 MPa), more preferably 1 to 7 MPa (eg, 2 to 7 MPa) It is an extent. The polymer having such characteristics has high mechanical strength at around room temperature (about 20 to 25 ° C.) and high fluidity at about 30 to 80 ° C. When the storage elastic modulus at 80 ° C. is “1”, the storage elastic modulus at 25 ° C. is, for example, 0.05 × 10 ³ to 10 × 10 ³ with respect to the storage elastic modulus at 80 ° C. (For example, about 0.1 × 10 ³ to 5 × 10 ³ , preferably about 0.2 × 10 ³ to 1 × 10 ³ , and more preferably about 0.3 × 10 ³ to 0.7 × 10 ³ ). The storage modulus of the crosslinked product can be measured by the method described in the examples.

In addition, the crosslinked product of the present invention (in particular, a crosslinked product of a copolymer in which a cyclic olefin and a chain olefin are combined in the above ratio) has a large molecular weight between crosslinking points, for example, 8,000 to 30,000, preferably 9,000 to 25,000. (For example, 9500 to 20000), and more preferably about 10000 to 18000 (for example, 10000 to 16000). Such a large inter-crosslink molecular weight indicates that the crosslinker has a loosely crosslinked structure with a low crosslink density. Therefore, although the crosslinked body behaves like a thermoplastic resin and flows when heated, the flow and deformation of the crosslinked body are regulated by crosslinking when the temperature is higher than a predetermined temperature, and unlike the thermoplastic resin, it has heat resistance. Therefore, when the molecular weight between crosslinking points is too small, the flowability decreases, and when the molecular weight between crosslinking points is too large, the heat resistance to flow deformation decreases. In addition, the molecular weight between crosslinking points of the crosslinked body can be determined by a conventional method, for example, a typical method using the rubber elasticity theory. In this method, the molecular weight between crosslinking points can be calculated by the following equation.

G = (ρRT) / M _X
(Wherein G is shear modulus (unit Pa), ρ is density (g / m ³ ), R is gas constant (8.314 J / K / mol), T is absolute temperature (K), and M _X is crosslinking Indicates point-to-point molecular weight (g / mol)
The shear modulus G can be measured by the storage modulus in a rubbery flat area (for example, 140 ° C., angular frequency 0.1 Hz) (the method of measuring the storage modulus is the same as above). Further, the density ρ can be measured by the Archimedes method, and the density of the polymer described in the book “Polymer Engineering and Science, MID-JULY, 1990, Vol. 30, No. 13, P753-761” can also be referred to.

The crosslinked product of the present invention is also excellent in transparency, and the haze (clouding value) may be, for example, 5% or less, preferably 2% or less (for example, 0) in a method according to JIS K7105. And more preferably about 0.1 to 1.5% (particularly 0.2 to 1%). In the present invention, since the proportion of the cyclic olefin in the cyclic olefin resin is appropriately adjusted, both the appropriate flexibility and high heat resistance can be achieved as described above, and the cyclic olefin resin is amorphous. The transparency or the light guiding property is also high, and the generation of haze can be suppressed.

In the present invention, haze can be measured at a thickness of about 100 μm. The haze includes external haze caused by asperities and the like on the surface of the measurement sample (film) and internal haze caused by microcrystals present in the film. In the case of the present invention, there is almost no internal haze and may show a haze of about 2% or less depending on the external haze of the film surface, but since there is almost no internal haze, the haze does not increase even when the thickness is increased.

The total light transmittance of the crosslinked product of the present invention is, for example, 80% or more, preferably 80 to 99%, more preferably 85 to 98% (particularly 90 to 95%) in a method (thickness 100 μm) according to JIS K7105. ) May be.

Furthermore, the ratio of light intensity at 454 nm to light intensity at 605 nm (454 nm / 605 nm) may be 3.0 or more, for example 3.0 to 3.7, preferably 3.1 to 3.7, More preferably, it is about 3.2 to 3.7.

The form of the crosslinked product of the present invention is not particularly limited, but when it is in the form of a film, the thickness of the film is about 20 to 400 μm, preferably 30 to 350 μm, more preferably 40 to 300 μm (eg 50 to 200 μm). It may be about 100 μm or more (eg, 100 to 400 μm), preferably about 150 μm or more (eg, 200 to 350 μm).

The cross-linked product of the present invention may be a conventional additive such as a cross-linking agent, a cross-linking accelerator, a cross-linking aid, an antioxidant, a heat stabilizer, a light stabilizer, a stabilizer such as a UV absorber, a plasticizer, You may contain the inhibitor, a flame retardant, etc. These additives may be used alone or in combination of two or more.

The crosslinked body of the present invention may be substantially free of a resin having a crosslinkable group (eg, a group having an ethylenically unsaturated bond, etc.). Furthermore, the crosslinker of the present invention may be substantially free of a crosslinker, a crosslinker, and a crosslinker in order to crosslink using an electron beam.

(Method of producing a crosslinked product)
The crosslinked body of the present invention is obtained by crosslinking the cyclic olefin resin, and the method of crosslinking is not particularly limited, and active rays such as ultraviolet rays, beta (β) rays, gamma (γ) rays, X rays, etc. Radiation (especially gamma rays) may be used, but it is easy to control and produced by crosslinking with high energy rays (electron beam or gamma rays) from the viewpoint of easy preparation of a novel crosslinked body having the above characteristics. It is also good. In particular, when crosslinking is carried out with an electron beam, it is possible to suppress oxidation due to heating, or yellowing can be prevented, and a crosslinked product having excellent transparency can be obtained. In the present invention, since a high energy electron beam is used, a crosslinking agent and a crosslinking accelerator (auxiliary agent) are unnecessary, and a highly stable crosslinked product can be efficiently produced. In particular, in irradiation with an electron beam, the cyclic olefin resin can be crosslinked at normal temperature (for example, a temperature of about 10 to 30 ° C.) without heating, and the crosslinking density can also be improved.

As a method of irradiating an electron beam, for example, a method of irradiating an electron beam by an exposure source such as an electron beam irradiation device can be used. The irradiation dose (dose) varies depending on the thickness of the cyclic olefin resin, but can be selected, for example, from the range of about 10 to 500 kGy (gray) (for example, 100 to 400 kGy), but the crosslink density is increased to improve heat resistance. From the point of view, it may be 200 kGy or more, for example, about 200 to 500 kGy, preferably about 220 to 450 kGy, and more preferably about 230 to 430 kGy (particularly about 250 to 400 kGy).

The acceleration voltage can be selected from the range of about 10 to 1000 kV (for example, 100 to 500 kV), but may be 150 kV or more from the viewpoint of improving heat resistance, for example, 160 to 400 kV, preferably 170 to 300 kV, More preferably, it may be about 180 to 250 kV.

As a method of irradiating a gamma ray, for example, a method of irradiating a gamma ray by an exposure source such as a gamma ray irradiation device can be used. The irradiation dose (dose) varies depending on the thickness of the cyclic olefin resin, but can be selected, for example, from the range of about 10 to 500 kGy (gray) (for example, 100 to 400 kGy), but the crosslink density is increased to improve heat resistance. From the point of view, it may be 200 kGy or more, for example, about 200 to 500 kGy, preferably about 220 to 450 kGy, and more preferably about 230 to 430 kGy (particularly about 250 to 400 kGy).

Note that irradiation with an electron beam or radiation may be performed in air, and may be performed in an inert gas (for example, nitrogen gas, argon gas, helium gas, etc.) atmosphere if necessary. In the present invention, the deformation of the cyclic olefin resin is suppressed even after the irradiation of the electron beam and the gamma ray.

The crosslinked product of the present invention can be obtained by using a conventional molding method for cyclic olefin resins, such as injection molding, extrusion molding, blow molding, vacuum molding, profile molding, injection pressing, press molding, gas injection molding A molded product having a desired shape can be obtained by crosslinking after forming into a shape (film or sheet, various three-dimensional shapes, etc.) according to the application by a method, compression molding, transfer molding, etc. .

The present invention will be described in more detail based on examples given below, but the present invention is not limited by these examples. In addition, the characteristic of the cyclic olefin resin obtained in the Example and the test piece was measured by the following method.

(Glass transition temperature and melting point)
The measurement was performed using a differential scanning calorimeter (“DSC 6200” manufactured by Seiko Instruments Inc.) under a nitrogen stream at a temperature rising rate of 10 ° C./minute.

(Gel fraction)
A 500 mg test piece was weighed into a 100 ml eggplant-type flask equipped with a condenser, 50 ml of toluene was further added, and the mixture was stirred at reflux temperature for 3 hours. Thereafter, the mixture was filtered, and the filter residue was dried under reduced pressure and then weighed to determine the gel fraction.

(Degree of crystallinity)
The obtained film was subjected to wide-angle X-ray measurement using an X-ray diffractometer (XRD, “RINT 1500” manufactured by Rigaku Corporation). Specifically, diffraction peak measurement was performed in the range of 2θ = 0 ° to 60 ° using CuKα.

(Haze)
The haze of the test pieces obtained in the examples was measured using a haze meter (NDH-500 manufactured by Nippon Denshoku Kogyo Co., Ltd.) in accordance with JIS K 7136.

(Tensile test)
About the test piece obtained in the Example, a JIS No. 2 dumbbell piece (width 6 mm) was punched out in the flow (MD) direction, and a tensile test was performed at 23 ° C./50% RH and a tensile speed of 500 mm / min.

(Light intensity ratio, outgoing light hue)
The test piece obtained in the example was cut into a strip having a thickness of 200 μm, a width of 2 cm, and a length of 8 cm. White light is made incident from the cut-out end of the strip by a white LED (manufactured by Nichia Corporation, trade name: NSPB 500S), and the light is transmitted through the film (optical path length: 8 cm), and from the other end The visible light spectrum of the emitted light was measured using a spectrophotometer (manufactured by Hamamatsu Photonics Co., Ltd., multi-channel spectrometer: PMA-11). Moreover, the hue of the emitted light was confirmed visually. The white LED used this time had a peak derived from the blue LED at 454 nm, and a broad spectrum of the fluorescent material was observed at a long wavelength of 500 nm or later. The light intensity ratio of 454 nm of the white LED alone to 605 nm, which is the complementary color of blue, was 3.7. It can be said that the closer the light intensity ratio is to 3.7, the better the light guide performance that the spectrum reproducibility is good.

Light intensity ratio = light intensity at 454 nm / light intensity at 605 nm.

(Linear expansion coefficient)
The test pieces obtained in the examples were subjected to linear expansion at 140 ° C. to 150 ° C. using a thermomechanical analyzer (EXSTAR TMA / SS 7100 manufactured by SII Nano Technology Inc.) in accordance with JIS K7197. The coefficients were measured.

(Viscoelastic measurement)
The test pieces of Examples and Comparative Examples were cut into a width of 5 mm and a length of 50 mm, and the distance between chucks was measured using a dynamic viscoelasticity measuring device (RSA-III manufactured by TA Instruments Japan Ltd.). The storage elastic modulus (E ′) was measured under the conditions of 20 mm, a temperature elevation rate of 5 ° C./min, and an angular frequency of 10 Hz.

(Molecular weight between crosslinking points)
The inter-crosslinking point molecular weight is obtained by substituting the data at a temperature of 140 ° C. and an angular frequency of 0.1 Hz obtained by the viscoelasticity measurement into the equation for calculating the inter-crosslinking point (G = (ρRT) / M _X ) Calculated. The density ρ (g / m ³ ) was 1.02.

Production Example 1 (Cyclic Olefin Resin A)
15 liters of toluene, 15 millimoles of triisobutylaluminum (TIBA), 0.75 millimoles of zirconium tetrachloride, 0.75 millimoles of anilinium tetrakis (pentafluorophenyl) borate are sequentially added to a 30 liter autoclave at room temperature under a nitrogen atmosphere. Then, 1.8 liters of a toluene solution containing 70% by weight of norbornene was added. After raising the temperature to 50 ° C., the reaction was carried out for 60 minutes while introducing ethylene continuously so that the ethylene partial pressure was 5 kgf / cm ² . After completion of the reaction, the polymer solution was poured into 15 liters of methanol to precipitate a polymer. The polymer was separated by filtration and dried to obtain cyclic olefin resin A (ethylene-norbornene copolymer A). The yield was 3.12 kg and the polymerization activity was 46 kg / g Zr (yield per 1 g of zirconium).

^{In 13} C-NMR, the sum of the peak based on ethylene unit and the peak based on methylene of 5 and 6 position of norbornene unit (around 30 ppm) and the peak based on methylene group of 7 position of norbornene unit (around 32.5 ppm) The norbornene content determined from the ratio was 8.6 mol%. The glass transition temperature was −1 ° C., the melting point was 80 ° C., and the crystallinity was 10%.

Comparative Example 1
Using cyclic olefin resin A obtained in Production Example 1, attach a T-die with a width of 150 mm to a small extruder (20 mmφ, L / D = 25 manufactured by Plastic Engineering Laboratory), and extrude temperature 200 ° C. The chill roll temperature was adjusted to 10 ° C., the take-up speed was adjusted, and a film-shaped test piece having a thickness of 100 μm was produced. The obtained test piece is irradiated with an electron beam at an acceleration voltage of 200 kV and a dose of 350 kGy using an EB irradiation apparatus (“Icon” manufactured by Iwasaki Electric Co., Ltd. “TYPE; CB 250/15/180 L”) at normal temperature in a nitrogen atmosphere. Cross-linked. The white LED was guided, but because of the crystalline polymer, Rayleigh scattering occurred, and the light emitted from the test piece was colored orange.

Example 1
Instead of cyclic olefin resin A, cyclic olefin resin (trade name “TOPAS9903”, manufactured by Topas Advanced Polymers GmbH, number average molecular weight 69000, glass transition temperature 33 ° C., norbornene content 20 mol%, crystallinity 0%) A film-shaped test piece was produced in the same manner as in Comparative Example 1 except that the electron beam was irradiated at an accelerating voltage of 200 kV and a dose of 250 kGy. The light emitted from the test piece was white because it was an amorphous polymer. Furthermore, the storage elastic modulus at 25 ° C. was 1480 MPa, the storage elastic modulus at 80 ° C. was 2.99 MPa, and the molecular weight between crosslinking points was 13,000.

Example 2
A film-shaped test piece was produced in the same manner as in Example 1 except that the electron beam was irradiated under the conditions of an accelerating voltage of 200 kV and a dose of 350 kGy. The light emitted from the test piece was white because it was an amorphous polymer. Furthermore, the storage elastic modulus at a temperature of 25 ° C. was 1520 MPa, the storage elastic modulus at a temperature of 80 ° C. was 3.04 MPa, and the molecular weight between crosslinking points was 11,000.

Example 3
A film-shaped test piece was produced in the same manner as in Example 1 except that the electron beam was irradiated under the conditions of an accelerating voltage of 200 kV and a dose of 150 kGy. The light emitted from the test piece was white because it was an amorphous polymer. Furthermore, the storage elastic modulus at 25 ° C. was 1510 MPa, the storage elastic modulus at 80 ° C. was 2.98 MPa, and the molecular weight between crosslinking points was 15000.

Example 4
Instead of cyclic olefin resin A, cyclic olefin resin (trade name "TOPAS9506" manufactured by Topas Advanced Polymers GmbH, number average molecular weight 66000, glass transition temperature 70 ° C, norbornene content 32 mol%, crystallinity 0%) A film-like test piece was produced in the same manner as in Comparative Example 1 except for using. The light emitted from the test piece was white because it was an amorphous polymer.

Example 5
The same as Example 1, except that irradiation is performed at a dose of 350 kGy using gamma ray irradiation apparatus (Nordion "JS10000HD", source cobalt -60, under atmosphere, normal temperature (in-chamber temperature 40 ° C) instead of electron beam irradiation. A film-like test piece was produced, and the light emitted from the test piece was white because it was an amorphous polymer, and the storage elastic modulus at a temperature of 25 ° C. was 1500 MPa and a storage elastic modulus at 80 ° C. It was 3.06 MPa and molecular weight between crosslinking points was 11,000.

Comparative example 2
Instead of cyclic olefin resin A, cyclic olefin resin (trade name "TOPAS 8007" manufactured by Topas Advanced Polymers GmbH, number average molecular weight 51000, glass transition temperature 80 ° C., norbornene content 42 mol%, crystallinity 0%) A film-like test piece was produced in the same manner as in Comparative Example 1 except for using. The light emitted from the test piece was white because it was an amorphous polymer.

Comparative example 3
Accelerated using cyclic olefin resin (trade name "TOPAS6013" manufactured by Topas Advanced Polymers GmbH, glass transition temperature 130 ° C, norbornene content 50 mol%, crystallinity 0%) instead of cyclic olefin resin A A film-shaped test piece was produced in the same manner as in Comparative Example 1 except that the electron beam was irradiated at a voltage of 200 kV and a dose of 250 kGy. The light emitted from the test piece was white because it was an amorphous polymer.

The monomer composition ratio and the electron beam irradiation conditions in Comparative Examples and Examples are shown in Table 1, and the results of evaluating the characteristics of the test pieces obtained in Comparative Examples and Examples are shown in Tables 2 and 3.

As apparent from the results of Tables 2 and 3, the crosslinked product of the present invention is high in transparency and excellent in mechanical properties.

The crosslinked product of the present invention can be used for molding materials in various fields, such as optical materials, electric and electronic materials, electric insulating materials, automobile parts materials, medical materials, construction and civil engineering materials and the like. Furthermore, since the crosslinked body of the present invention can simultaneously achieve both heat resistance and flexibility and is excellent in transparency, various electric / electronic devices or optical devices, for example, switch members such as portable devices, home appliances, and control devices It can be used as Specifically, members such as mobile phones, gaming machines, mobile devices, touch panels, car navigation systems, watches, calculators, televisions, personal computers (for example, key top sheets, key mat sheets, light guide sheets, reflective sheets, OCA It is also useful as a tape (such as high transparency adhesive transfer tape or coreless tape for optics).

In particular, the cross-linked body of the present invention is a material having a novel property of achieving both high transparency, low temperature softening property and heat resistance, and an optical sealing material (for example, OCA tape, organic electroluminescence (EL) sealing) Especially suitable for

Claims

A crosslinked product of a chain olefin-cyclic olefin copolymer comprising a chain olefin and a cyclic olefin as a polymerization component,
The cyclic olefin comprises a bicyclic olefin,
The proportion of the cyclic olefin is more than 15 mol% and 40 mol% or less based on the total of the chain olefin and the cyclic olefin, and the glass transition temperature of the chain olefin-cyclic olefin copolymer is Crosslinked body at 20-80 ° C.
A crosslinked product of a chain olefin-cyclic olefin copolymer comprising a chain olefin and a cyclic olefin as a polymerization component,
The cyclic olefin comprises a bicyclic olefin,
The proportion of the cyclic olefin is more than 15 mol% and 40 mol% or less with respect to the total of the chain olefin and the cyclic olefin, and the crystallinity of the chain olefin-cyclic olefin copolymer is Crosslinked body having 1% or less.
The crosslinked product according to claim 1 or 2, wherein the crystallinity of the linear olefin-cyclic olefin copolymer is 0.5% or less.
The crosslinked product according to any one of claims 1 to 3, which has a haze of 2% or less according to JIS K7136.
The crosslinked product according to any one of claims 1 to 4, wherein the glass transition temperature of the linear olefin-cyclic olefin copolymer is 30 to 50 ° C.
The crosslinked product according to any one of claims 1 to 5, wherein the cyclic olefin is norbornene, and the molar ratio of the chain olefin to the cyclic olefin is chain olefin / cyclic olefin = 84/16 to 75/25. .
7. The gel composition according to any one of claims 1 to 6, which has a breaking elongation of 100 to 400% at a thickness of 100 μm according to JIS K 7127 and a gel fraction of at least 70% by weight measured by refluxing with toluene for 3 hours. The crosslinked body as described in.
The crosslinking according to any one of claims 1 to 7, wherein the storage elastic modulus at a temperature of 25 ° C is 100 to 4000MPa, the storage elastic modulus at a temperature of 80 ° C is 0.01 to 10MPa, and the molecular weight between crosslinking points is 8000 to 30000. body.
The crosslinked product according to any one of claims 1 to 8, which does not substantially contain a resin having a crosslinkable group and a crosslinking agent.
The crosslinked body according to any one of claims 1 to 9, which is an electron beam crosslinked body.
The crosslinked product according to any one of claims 1 to 10, which is in the form of a sheet and is a sealing material for an optical element.
A method for producing a crosslinked product according to claim 1, wherein the linear olefin-cyclic olefin copolymer is crosslinked by electron beam or radiation.
The method according to claim 12, wherein the crosslinking is carried out by an electron beam without heating.
The method according to claim 12 or 13, wherein the crosslinking is performed by an electron beam having an acceleration voltage of 150 kV or more and an irradiation dose of 200 kGy or more.